A variety of technologies have been employed for pumping liquids from one location to another. The most commonly used are mechanical devices. The mechanical pumps broadly fall into two categories, centrifugal pumps and displacement pumps. Centrifugal pumps employ the centrifugal force created by rotary motion to move water from one location to another. Typically, these pumps must be primed. They ordinarily do not operate well with fluids that have high viscosity. At higher speeds, cavitation effects may develop which destroy the efficiency of the pump. Additionally, these pumps require their moving parts to fit with reasonably close tolerances. If the tolerances are too large, so that there is backflow or leakage of the fluid around the driving moving parts, then there is loss of efficiency of the pump or the pump might stop operating altogether.
Displacement pumps take a variety of forms, including reciprocating pistons or rotary devices. Not all forms of these pumps require priming and certain forms of these pumps can operate, at least at low speeds, with liquids having a high degree of viscosity. Ordinarily, the inlets of these pumps must be submerged completely within the liquid to be pumped or the pump will not operate at acceptable efficiency or operate at all. Additionally, displacement rotary pumps require very close tolerances to effectively operate. The displacement reciprocating piston pumps do not require tolerances as close as the rotary pumps, but reasonably close tolerances are required if the reciprocating pump is to operate at expected efficiencies.
These types of mechanical pumps are particularly subject to fouling by suspended particles or solid matter in the liquid to be pumped. Any kind of floating debris that is pulled into the pump inlet can foul or destroy the pump. For these reasons, these pumps ordinarily require some degree of attention from an operator. This is especially true where water levels may rise and fall or where the condition of the liquid to be pumped varies widely.
Endless belts or hose like collectors have been employed in specialized applications usually involving high viscosity hydrocarbons. Here, an endless belt or tube rotates on the surface of a liquid usually contaminated by hydrocarbons. The hydrocarbon materials, which are floating on the surface of water, adhere to the belt as the belt moves out off the surface of the liquid containing the high viscosity hydrocarbons. The belt moves to a collector where the belt is scraped to remove the hydrocarbons adhering to the surface of the belt, which are then collected for subsequent disposal. The belt, after being scraped, returns to the water to begin the process over again. An example of this type of technology is seen in U.S. Pat. No. 3,508,663, issued to Brill on Aug. 28, 1970. Similar technology is seen in U.S. Pat. No. 3,617,552, issued to Will and Grutsch on Nov. 2, 1971, which uses a revolving polyurethane foam belt to collect both water and hydrocarbons. The belt is squeezed twice to first remove the water and then again to remove the hydrocarbons. U.S. Pat. No. 5,080,781, issued to Evins on Jun. 14, 1992 discloses an endless absorption belt which collects low viscosity hydrocarbons from a well. This invention is ordinarily placed into a well bore so that the hydrocarbons are first removed from the water then pumped to the surface where they are collected for use. The above devices have been designed primarily for removal of hydrocarbons and separating them from water. Their applications are usually in pollution clean ups, hydrocarbons monitoring wells, and the like.
There are many application where no conventional pump technology meets all of the needs of the applications. In agricultural applications, frequently muddy water or water with particulate matter must be pumped. The degree of particulate matter suspended in the water may vary widely from time to time. Additionally, bits of debris, small fish or other aquatic life may also be present in the water. This type of foreign material can easily foul or destroy conventional mechanical pumps. Additionally, the water level may vary widely. The close mechanical tolerances required by many pump types require that the fluid pumped be relatively free of foreign bodies or other material that may affect the required tolerances. It may be inappropriate to pump when a water level is below a certain level. While floats and other sensors may be employed to control the pump, these sensors are subject to fouling or malfunction. In many types of mechanical pumps if the inlet is exposed to air, the pump will cease operating and will not operate again until the pump is again primed. Therefore, if the water level falls below the inlet while the pump is operating, the pump cannot operate again without operator intervention. Thus, a self-priming pump is a desirable feature. In agricultural applications and in environmental wastewater management applications, it may be desirable not only to move water from one place to another, but also to aerate the water that is being pumped as well as the water that is located within the vicinity of the pump inlet. A pump that aerates the liquid pumped as well as aerates around the pump inlet is desirable in many applications.
Consequently, it would be an advance in the technology to devise an endless belt pump that could not only pump high and low viscosity hydrocarbons, but also pump water. The pumping device should be mechanically simple. It should require no close tolerances and a minimum of moving parts. It should be resistent to fouling from particulate matter or other foreign bodies in the liquid pumped. The pump should operate without priming. Exposing the pump inlet to air should not harm the pump or impair its efficiency. The pump should be resistent to changes in environmental temperatures, including freezing temperatures. The pump should pump a roughly linearly increasing volume at its speed is linearly increased. The pump should be durable and require little, if any, operator control other than turning the pump on and off. The pump should require little energy to operate. The pump should aerate as well as pump.